I cannot remove or add programs.

I have picked up something and cannot find it. When I delete a program from my
hard drive or if I download something to my hard drive and then I reboot, everything that was deleted is back and what was downloaded is gone. I have detected trojans and viruses, but when I remove them and reboot they are back again.

I don't know what "Steady State" is. I am using XP.I have ran every Virus protection and several malwares programs. If they found anything, they cleaned them, but when I rebooted they were right back as before.